1. Field of the Invention
The invention relates to novel gasoline-soluble polyoxyalkylene ester compounds, to concentrates comprising the polyoxyalkylene esters dissolved in hydrocarbon solvents and to haze-free, ORI-inhibited and deposit-resistant motor fuel compositions comprising the polyoxyalkylene esters.
Motor fuel compositions comprising the polyoxyalkylene esters of the instant invention are haze-free, ORI-inhibited and have a reduced tendency to form deposits.
2. Information Disclosure Statement
Combustion of a hydrocarbonaceous motor fuel in an internal combustion engine generally results in the formation and accumulation of deposits on various parts of the combustion chamber as well as on the fuel intake and exhaust systems of the engine. The presence of deposits in the combustion chamber seriously reduces the operating efficiency of the engine. First, deposit accumulation within the combustion chamber inhibits heat transfer between the chamber and the engine cooling system. This leads to higher temperatures within the combustion chamber, resulting in increases in the end gas temperature of the incoming charge. Consequently, end gas auto-ignition occurs, which causes engine knock. In addition the accumulation of deposits within the combustion chamber reduces the volume of the combustion zone, causing a higher than design compression ratio in the engine. This, in turn, also results in serious engine knocking. A knocking engine does not effectively utilize the energy of combustion. Moreover, a prolonged period of engine knocking will cause stress fatigue and wear in vital parts of the engine. The above-described phenomenon is characteristic of gasoline powered internal combustion engines. It is usually overcome by employing a higher octane gasoline for powering the engine, and hence has become known as the engine octane requirement increase (ORI) phenomenon. It would therefore be highly advantageous if engine ORI could be substantially reduced or eliminated by preventing deposit formation in the combustion chamber of the engine.
An additional problem common to internal combustion engines relates to the accumulation of deposits in the carburetor which tend to restrict the flow of air through the carburetor at idle and at low speed, resulting in an over rich fuel mixture. This condition also promotes incomplete fuel combustion and leads to rough engine idling and engine stalling. Excessive hydrocarbon and carbon monoxide exhaust emissions are also produced under these conditions. It would therefore be desirable from the standpoint of engine operability and overall air quality to provide a motor fuel composition which minimizes or overcomes the above-described problems.
Deposit-inhibiting additives for use in motor fuel compositions are well known in the art. However, conventional additives may cause hazing of the motor fuel. Hazy motor fuels are unacceptable by the public since they may indicate a problem with the fuel, such as the presence of undesired contaminants. It would therefore be desirable to provide a haze-free motor fuel composition which is deposit-resistant and ORI-inhibited.
In recent years, numerous fuel detergents or "deposit control" additives have been developed. These materials when added to hydrocarbon fuels employed internal combustion engines effectively reduce deposit formation which ordinarily occurs in carburetor ports, throttle bodies, venturis, intake ports and intake valves. The reduction of these deposit levels has resulted in increased engine efficiency and a reduction in the level of hydrocarbon and carbon monoxide emissions.
A complicating factor has, however, recently arisen. With the advent of automobile engines that require the use of non-leaded gasolines (to prevent disablement of catalytic converters used to reduce emissions), it has been difficult to provide gasoline of high enough octane to prevent knocking and the concomitant damage which it causes. The difficulty is caused by octane requirement increase, herein called "ORI", which is due to deposits formed in the combustion chamber while the engine is operating on commercial gasoline.
The basis of the ORI problem is as follows: each engine, when new, requires a certain minimum octane fuel in order to operate satisfactorily without pinging and/or knocking. As the engine is operated on any gasoline, this minimum octane increases and, in most cases, if the engine is operated on the same fuel for a prolonged period will reach equilibrium. This is apparently caused by an amount of deposits in the combustion chamber. Equilibrium is typically reached after 5000 to 15,000 miles of automobile operation.
Octane requirement increase measured in particular engines with commercial gasolines will at equilibrium vary from 5 or 6 octane units to as high as 12 or 15 units, depending upon the gasoline compositions, engine design and type of operation. The seriousness of the problem is thus apparent. The ORI problem exists in some degree with engines operated on leaded fuels. U.S. Pat. Nos. 3,144,311 and 3,146,203 disclose lead-containing fuel compositions having reduced ORI properties.
It is believed, however, by many experts, that the ORI problem, while present with leaded gasolines, is much more serious with unleaded fuel because of the different nature of the deposits formed with the respective fuels, the amount of the octane requirement increase, and because of the lesser availability of high-octane non-leaded fuels. This problem is compounded by the fact that the most common means of enhancing the octane of unleaded gasoline, increasing its aromatic content, also appears to increase the eventual octane requirement of the engine. Furthermore, some of the presently used nitrogen-containing deposit control additives with mineral oil or polymer carriers appear to contribute significantly to the ORI of engines operated on unleaded fuel.
It is, therefore, highly desirable to provide fuel compositions which contain deposit control additives which effectively control deposits in intake systems (carburetor, valves, etc.) of engines operated with fuels containing them, but do not contribute to the combustion chamber deposits which cause increased octane requirements.
Co-assigned U.S. patent application Ser. No.000,230, filed Jan. 1, 1987, now abandoned, now U.S. Pat. No. 4,810,261 discloses a novel gasoline-soluble reaction product and the use of the reaction product as an ORI-inhibitor in motor fuel compositions. The novel reaction product is obtained by reacting:
(i) about 1 mole of a dibasic acid anhydrid PA0 (ii) 1-2 moles of novel polyoxyalkylene diamine; and PA0 (iii) 1-2 moles of a hydrocarbyl polyamine.
Co-assigned U.S. Pat No. 4,581,040 teaches the use of a reaction product as a deposit inhibitor additive in fuel compositions. The reaction product taught is a condensate product of the process comprising;
(i) reacting a dibasic acid anhydride with a polyoxyisopropylenediamine of the formula ##STR1## where x is a numeral of about 2-50, thereby forming a maleamic acid; (ii) reacting said maleamic acid with a polyalkylene polyamine, thereby forming a condensate product; and PA1 (iii) recovering said condensate product. PA1 (i) the reaction product of maleic anhydride, a polyether polyamine containing oxyethylene and oxypropylene ether moieties, and a hydrocarbyl polyamine; and PA1 (ii) a polyolefin polymer/copolymer as an additive in motor fuel compositions to reduce engine ORI.
Co-assigned U.S. Pat. No. 4,639,336 discloses the use of the mixture of:
Co-assigned U.S. Pat. No. 4,659,337 discloses the use of the reaction product of maleic anhydride, a polyether polyamine containing oxyethylene and oxypropylene ether moieties, and a hydrocarbyl polyamine in a gasoline motor fuel to reduce engine ORI and provide carburetor detergency.
U.S. Pat. No. 4,604,103 discloses a motor fuel deposit control additive for use in internal combustion engines which maintains cleanliness of the engine intake systems without contributing to combustion chamber deposits or engine ORI. The additive disclosed is a hydrocarbyl polyoxyalkylene polyamine ethane of molecular weight range 300-2500 having the formula ##STR2## where R is a hydrocarbyl radical of from 1 to about 30 carbon atoms; R' is selected from methyl and ethyl; x is an integer from 5 to 30; and R" and R'" are independently selected from hydrogen and--(CH.sub.2 CH.sub.2 NH--).sub.y H where y is an integer from 0-5.
U.S. Pat. No. 4,357,148 discloses the use of the combination of an oil-soluble aliphatic polyamine component containing at least one olefinic polymer chain and having a molecular weight range of 600-10,000 and a polymeric component which may be a polymer, copolymer, hydrogenated polymer or copolymer, or mixtures thereof having a molecular weight range of 500-1500 to reduce or inhibit ORI in motor fuels.
U.S. Pat. No. 4,191,537 discloses the use of a hydrocarbyl polyoxyalkylene aminocarbonate, having a molecular weight range of 600-10,000 and also having at least one basic nitrogen atom per aminocarbonate molecule, to reduce and control ORI in motor fuels.
Co-assigned U.S. Pat No. 3,502,451 discloses the use of C.sub.2 -C.sub.4 polyolefin polymers or hydrogenated polymers having a molecular weight range of 500-3500 in motor fuels to eliminate or reduce deposition on the intake valves and ports of an internal combustion engine.
U.S. Pat. No. 3,438,757 discloses the use of branched chain aliphatic hydrocarbyl amines and polyamines having molecular weights in the range of 425-10,000 to provide detergency and dispersancy in motor fuels.
Co-assigned U.S. Pat. No. 4,316,991 discloses a modified polyol compound having a molecular weight range of 2000-7000, produced by reacting an initiator having an active hydrogen functionality of 3-4, one or more alkylene oxides, and an epoxy resin.
U.S. Pat. No. 3,654,370 discloses a method of preparing polyoxyalkylene polyamines by treating the corresponding polyoxyalkylene polyol with ammonia and hydrogen over a catalyst prepared by the reduction of a mixture of nickel, copper, and chromium oxides. The polyoxyalkylene polyamines formed are of the formula: ##STR3## wherein R is the nucleus of an oxyalkylation-susceptible polyhdric alcohol containing 2-12 carbon atoms and 2-8 hydroxyl groups, Z is an alkyl group containing 1-18 carbon atoms, X and Y are hydrogen or Z, n has an average value of 0-50 and m is an integer of 2-8 corresponding to the number of hydroxyl groups in the polyhydric alcohol.
U.S. Pat. No. 3,535,307 discloses the preparation of high molecular weight polyether block copolymers by the sequential alkoxylation of a polyfunctional initiator with alkylene epoxide components.
Co-assigned U.S. application Ser. No. 07/468,326 filed Jan. 22, 1990, now abandoned and refiled Feb. 25, 1991 as U.S. application Ser. No. 660,069, now abandoned and refiled Jul. 15, 1991 as U.S. application Ser. No. 730,134, discloses ORI control additives comprising various esters of carboxylic acids, including N-acyl sarcosinates, and polyether polyols including segments of oxyethylene, oxypropylene and oxybutylene.
Co-assigned U.S. Pat. No. 4,747,851 discloses ORI additives comprising polyoxyalkylene diamine compounds in which the polyoxyalkylene backbone includes combinations of oxyethylene, oxypropylene and oxybutylene units.
U.S. Pat. No. 3,879,308 discloses various ester compounds which are stated to be useful as additives for fuels or lubricants. These carboxylic acid components of the esters contain at least 30 aliphatic carbon atoms exclusive of the carboxyl group, and are reacted with various "polyoxyalkylene alcohol demulsifiers," disclosed in col. 7 as encompassing various oxyalkylene groups and having molecular weights of about 1000 to 10,000.
U.S. Pat. No. 4,617,026 discloses additives for reducing motor fuel consumption comprising hydroxyl-containing esters of monocarboxylic acids and glycols in which the diols can be alkylene glycols or oxalkane diols (i.e., polyalkylene glycols in which the alkane is a
straight chain hydrocarbon of 2-5 carbon atoms). The carboxylic acids can have 12 to 30 carbon atoms, including aliphatic, saturated or unsaturated straight chain or branched components.
Applicant Sung's U.S. Pat. No. 4,758,247 disclosed reaction products of certain N-acyl sarcosine compounds and certain polyoxyalkylene polyols, which products are useful as ORI reduction additives. The reaction products are characterized by the formula: ##STR4## wherein R is a C.sub.8 -C.sub.24 alkyl radical, R' is H, CH.sub.3 or C.sub.2 H.sub.5, a+c has a value ranging from 1 to 20 and b has a value ranging from 5 to 50.
As discussed above, despite the extensive efforts to control ORI phenomena, the increasing use of unleaded gasolines has created even greater demands for additives which are more effective in inhibiting or controlling ORI, particularly in engines operating on unleaded gasoline.